120 POWER DISTRIBUTION FOR ELECTRIC RAILROADS. 
Unless some one locality shows marked advantage as 
a point for the cheap production of power, there is little 
cause fora principal station, for a better distribution can be 
had from two or more stations of nearly the same output, 
each taking care of its own portion of the general network. 
This is evident from two separate considerations. First, 
the cost of power per kilowatt hour is less, and second, the 
stations can reinforce each other to better advantage when 
they are tolerably uniform. If separate stations are to be 
used at all, the whole district is on the average better 
served in this way. These matters however usually settle 
themselves in the process of natural growth without oppor- 
tunity for theoretical adjustment. 
In distributed stations for interurban and long distance 
work, approximate equality is the rule except as local sub- 
urban traffic may call for separate treatment. 
The two stations of the Akron, Bedford & Cleveland 
Railway already mentioned are thoroughly typical of mod- 
ern practice in this respect. Fig. 68 shows the interior of 
the Cuyahoga Falls substation of thisroad. It is specially 
interesting as being adapted for transformation into a 
power transmission station, if growth of the road should 
render such a change desirable at some future time. The 
generators, as already mentioned, are composite machines, 
supplied with the ordinary commutator and also with 
a set of outboard collecting rings to deliver from the arm- 
ature winding polyphase currents which would otherwise 
be commutated in the ordinary way and sent out upon the 
line as continuous current. Each machine is of 250 k. w. 
capacity and delivers either continuous current at 500 volts 
or alternating currents at 380 volts and 3800 alternations 
per minute. Within reasonable limits both kinds of 
current can be delivered at once. Although at present 
the only use of the alternating current is fora compara- 
tively trivial amount of lighting, by installing a transmis- 
sion line with raising and reducing transformers it becomes 
an easy matter to exchange power between the two stations, 
in case of accident to either of the steam plants or to trans-